This application claims the priority of German Application No. 196 53 148.9 filed Dec. 19, 1996 in Germany, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a telescopically compressible wheel suspension, particularly for a front wheel of a motorcycle.
German Patent Document DE 37 25 983 A1 describes a telescopic spring strut, particularly for front wheel forks of motorcycles or the like, having a standpipe which is constructed as an interior pipe and a slide pipe which is constructed as the exterior pipe and which surrounds the lower end of the standpipe, both pipes being slidably in the axial direction disposed in one another. The slide pipe forms a lubricant container for accommodating a lubricant which increases the slidability of the connection of the standpipe and the slide pipe during their axial displacement with respect to one another. For this purpose, the slide pipe is filled with a lubricant and the standpipe is pushed in, which results in a lubricant level in the standpipe which has the reference number 9.
This is necessary because the lubrication of the uppermost slide bearing between the standpipe and the slide pipe must be ensured in any operating condition. Thus, for example, the fork legs of motorcycle forks are filled with oil up to a corresponding level. This also applies to the fork legs of motorcycle forks in the case of which the slide pipe is guided by way of at least one trailing arm which is mounted to be swivellable about a frame-fixed transverse axis of the vehicle, this trailing arm being supported fixed to the frame by way of a spring strut.
Particularly for motorcycle forks which permit large spring travels and are stiff, and thus have a large length and diameter, high oil filling quantities are required in order to ensure the lubrication of the uppermost slide bearing. This raises the weight and the costs of the motorcycle fork. The weight increase has a particularly negative effect because the weight of the oil in the slide pipe is added to the unsprung masses of the motorcycle.
It is therefore an object of the invention to limit, in the case of a telescopically compressible wheel suspension, the amount of lubricant for the slide-bearing-disposed telescopic guiding between a standpipe and a slide pipe and thus save weight, particularly on unsprung parts.
According to the invention, this and other objects have been achieved by providing a telescopically compressible wheel suspension for a front wheel of a motorcycle, comprising at least one standpipe, at least one slide pipe, said standpipe and said slide pipe being telescopically slidable in one another in an axial direction via at least one slide bearing, at least one of said standpipe and said slide pipe defining an interior space for receiving a lubricant, and a molded body disposed in said interior space.
According to the invention, in the case of a telescopically compressible wheel suspension having at least one standpipe and one slide pipe which are telescopically slidably guided in one another in the axial direction via at least one slide bearing and form a lubricant container, a molded body is inserted at least in a partial area of the slide and/or standpipe where at least a portion of the lubricant is situated, which molded body reduces by means of at least a portion of its volume, the lubricant amount required up to a defined level.
The insertion of a molded body in the standpipe and/or slide pipe of a telescopically compressible wheel suspension has the advantage that the molded body, because of its volume, reduces the amount of lubricant, such as oil, which is required for reaching a defined level. If the specific weight of the molded body is lighter than that of the lubricant, the weight of the wheel suspension will be reduced. With a lower weight of the unsprung masses of the wheel suspension, the suspension and damping behavior of the wheel suspension and therefore the handling of the vehicle will improve.
The saving of oil reduces the costs if the price of the molded body is lower.
Among others, an embodiment of the invention is particularly advantageous in which the slide pipe is guided by way of at least one trailing arm which is linked to be swivellable about a frame-fixed transverse axis of the vehicle and which is supported fixed to the vehicle frame via a spring device and/or damping device. Such a wheel suspension, in the case of which the spring device and/or damping device, for example, a spring strut, is not integrated in the telescopic fork, has a very large volume in the standpipe and slide pipe which are telescopically guided inside one another. By inserting a molded body, for example, a hollow, tightly closed cylinder consisting of a tube closed on both sides, coaxially in the slide pipe, which cylinder extends into the standpipe, a large amount of lubricant can be saved. The molded body takes up a substantial portion of the volume of the interior space for lubricant, for example, at least 50% thereof, and preferably at least 75% thereof.
With the exception of a gap, which is required so that the standpipe can freely move in the slide pipe, the hollow space of the slide pipe is filled by the hollow molded body made of a plastic material and/or of aluminum. Now only a lubricant quantity, such as oil, must be filled in which fills in the space between the molded body and the slide pipe and standpipe. Since the hollow molded body has a lower specific weight than the oil, the wheel suspension as a whole will be lighter.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.